It is known that 1,2-dihydropyridine compounds including 3-(2-cyanophenyl)-5-(2-pyridyl)-1-phenyl-1,2-dihydropyridin-2-one have AMPA receptor antagonistic activity and/or kainic acid receptor inhibitory activity and are useful as therapeutic agents for Parkinson's disease and the like (see Patent Documents 1 and 2).
Example 7 of patent Document 1 and Example 1X of patent Document 2 discloses free forms of 3-(2-cyanophenyl)-5-(2-pyridyl)-1-phenyl-1,2-dihydropyridin-2-one. Patent Document 1 discloses “The compound according to (1), salts thereof or hydrates of the foregoing, which is any one of compounds selected from (snip), 3-(2-cyanophenyl)-5-(2-pyridyl)-1-phenyl-1,2-dihydropyridin-2-one, (snip).” (Patent Document 1, page 13, 13th line to page 20, 18th line); and for exemplary salts thereof, there has been made a general disclosure that “There is no particular limitation for “a salt” in the specification of the present application so far as it forms a salt with the compound of the present invention and is a pharmacologically acceptable one. Preferably, salt with a hydrogen halide (such as hydrofluoride, hydrochloride, hydrobromide or hydroiodide), salt with an inorganic acid (such as sulfate, nitrate, perchlorate, phosphate, carbonate or bicarbonate), salt with an organic carboxylic acid (such as acetate, trifluoroacetate, oxalate, maleate, tartrate, fumarate or citrate), salt with an organic sulfonic acid (such as methanesulfonate, trifluoromethanesulfonate, ethanesulfonate, benzenesulfonate, toluenesulfonate or camphor-sulfonate), salt with an amino acid (such as aspartate or glutamate), salt with a quaternary amine, salt with an alkaline metal (such as sodium salt or potassium salt) and salt with an alkaline earth metal (such as magnesium salt or calcium salt). More preferred examples of the “pharmacologically acceptable salt” are hydrochloride, oxalate, etc.” (Patent Document 1, page 50, 9th line from bottom to page 51, 4th line).
However, although Patent Documents 1 and 2 disclose 3-(2-cyanophenyl)-5-(2-pyridyl)-1-phenyl-1,2-dihydropyridin-2-one, they do not describe any salt thereof in the context of a specific example.
[Patent Document 1] WO 01/96308
[Patent Document 2] WO 06/04107